Hidden sector effects on double Higgs production near threshold

Rogerio Rosenfeld

Instituto de Física Teórica UNESP

VIII Simpósio Latinoamericano de Física de Altas Energias                  SILAFAE 2010 – Valparaíso – Chile

Work done with Alexandra Oliveira (arXiv:1009.4497)

Dedicated to the memory of Olivier Espinosa

Idea:

• many BSM models with new interactions in the Higgs sector: “Higgs portal”

• new interactions in the Higgs sector could lead to enhancements in Higgs pair production near threshold (light Higgs has weak self-interactions)

H-H bound states (Higgsium, Grinstein and Trott 07)

• gluon distribution functions are largest near threshold.

...

Idea:

Effective ggHH vertexPlehn, Spira and Zerwas (96)

new scalar particle

Possible enhancement in Higgs pair production near thresholddue to new physics:

Analogous to Sommerfeld enhancements invoked in annihilation of DM particles and similar to QCD corrections to top quark pair production near threshold:

Fadin and Khoze(87) Fadin, Khoze and Sjostrand (90)Strassler and Peskin (91)Hagiwara, Sumino and Yokoya (08)

Toy model:

Use optical theorem to find correction to the cross section:

is the amplitude for gg scattering via a higgs loop.

Goal: compute this amplitude in the nonrelativistic limit includingcontributions from the hidden sector.

Summing up ladder diagrams:

Integral Bethe-Salpeter equation:

Complete scattering amplitude

Nonrelativistic approximation (after Fourier transform) results in a Schroedinger-like equation:

Solve equation numerically.

Enhancement of the cross section:

Enhancement depends on:

“strength of new interaction”

Solid line: SMk= 0.01, 0.1, 0.3

Solid line: SMk= 0.1, 0.7 and 1

Large enhancements for large couplings:

Peaks are due to HH bound states below threshold

Conclusions

• Initial study on the enhancement of Higgs pair production near threshold due to new physics in Higgs sector;

• Enhancement occurs for strong couplings;

• Simplest model with an extra scalar field does not lead to enhancements because of mixing:

• Signal: excess of 4 gauge bosons production below Higgs pair threshold (small background)

ICTP-South American Institute for Fundamental Research

November 8

Agreement between the State University of São Paulo (UNESP) and ICTP:• new institute will be hosted by IFT-UNESP• UNESP will hire 5 researchers in 5 years (light teaching load) selected by aninternational scientific committee and 3 administrative staff• ICTP will help in organizing events and raising funds